The Collaborative International Dictionary of English v.0.48:

Compassion \Com*pas"sion\, n. [F., fr. L. compassio, fr. compati
   to have compassion; com- + pati to bear, suffer. See
   Patient.]
   Literally, suffering with another; a sensation of sorrow
   excited by the distress or misfortunes of another; pity;
   commiseration.
   [1913 Webster]

         Womanly ingenuity set to work by womanly compassion.
                                                  --Macaulay.

   Syn: Pity; sympathy; commiseration; fellow-feeling; mercy;
        condolence. See Pity.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Compassion \Com*pas"sion\, v. t.
   To pity. [Obs.] --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

compassion
    n 1: a deep awareness of and sympathy for another's suffering
         [syn: compassion, compassionateness]
    2: the humane quality of understanding the suffering of others
       and wanting to do something about it [syn: compassion,
       pity]

Moby Thesaurus II by Grady Ward, 1.0:

66 Moby Thesaurus words for "compassion":
   acceptance, affectionateness, benevolence, benignancy, benignity,
   brotherhood, charity, clemency, clementness, commiseration,
   condolence, easiness, easygoingness, empathy, favor, feeling,
   feeling of kinship, fellow feeling, forbearance, forbearing,
   forgiveness, fraternal feeling, gentleness, goodness,
   goodness of heart, grace, graciousness, heart of gold, humaneness,
   humanity, kindheartedness, kindliness, kindly disposition,
   kindness, laxness, lenience, leniency, lenientness, lenity,
   loving kindness, mercifulness, mercy, mildness, mitigation,
   moderateness, niceness, pardon, pathos, patience, pity, quarter,
   relief, reprieve, rue, ruth, self-pity, softheartedness, softness,
   soul of kindness, sympathy, tenderheartedness, tenderness,
   tolerance, warmheartedness, warmth, warmth of heart